"In a situation of constitutional and legal ambiguity, it will be difficult for us to proceed," Trital said in a statement.
"Therefore, we have decided to inform the government that it is not possible to hold elections... On November 22," Trital said.
They further pointed out the need for political consensus to hold the fresh elections.
Prime Minister Baburam Bhattarai had dissolved the 601-member Constituent Assembly and had announced fresh elections to it on November 22.
The term of the Constituent Assembly had expired on May 27 without the promulgation of the new constitution, after which Bhattarai had made the "unilateral" announcement.
The opposition parties have been protesting the announcement, questioning its constitutionality.
The opposition parties have also declared that they will boycott the Constituent Assembly elections announced unilaterally by the government.